This week I think I met my favorite paper thus far - Buffington et al.'s Microbial Reconstitution Reverses Maternal Diet-Induced Social and Synaptic Deficits in Offspring. It's probably because I've never had any experience with the "gut-brain axis", but the idea of it is so incredibly interesting. So as someone who's never heard of this, the idea that the introduction of bacteria could alter neurochemistry and behavioral effects is mind-blowing.
Another reason I really loved the paper was the research design. I felt that as I was reading it, I would come up with questions that were answered immediately in the next section. It was intuitive and thorough. The results that stood out to me were the fact that co-housing of MHFD offspring with MRD was sufficient to exchange bacteria and reverse behavioral deficits. Additionally, I found it interesting that germ-free mice had comparable symptoms to MHFD offspring. Also, I thought it was important to note that both germ-free and MHFD mice had anxiety behaviors that could not be alleviated using L. reuteri. Buffington touches on this in the end saying that a combination of probiotics may be necessary to alleviate various symptoms (that's also something I thought was incredible, we could be cognitively tied and dependent on our gut bacteria - wow).
Although I loved this paper, I came up with a lot of questions (maybe some that I'll look into for my final paper). First, and most obviously, how does a high-fat maternal diet lead to a change in gut bacteria? While the paper acknowledges that this is unknown, I think it's essential to actually addressing their goal to "understand the neurobiological mechanism by which maternal obesity affects offspring behavior and brain function". Also, could this bacteria, on a control mouse, result in even higher levels of synaptic plasticity in the VTA and oxytocin production? The paper mentions briefly that addition of the bacteria to the MRD mice don't show anything but I think if the exact mechanism is unknown, it's worth looking into. Additionally, I would have preferred an introduction to the bacteria (for MHFD offspring) earlier than week 4, because that could have potentially acted upon anxiety behaviors that had already been established. And ultimately, what is the mechanism that links gut bacteria to the brain? Such a cool concept and I'm excited to learn more about it!